Colloid & Nanoparticle Transport







X-ray microtomograph of glass bead porous media with thiosulfate-Au-coated hollow glass microspheres (18 micron) faintly visible in grain to grain contacts near center of image [Li et al., 2005].


Dr. Xiqing Li at work in his lab at Beijing University

Christina Brow

Christina Brow backpacking in the Columbia River Gorge as a break from her Ph.D. studies at OHSU



Long exposure TIRF images of: (top) colloids moving along surface with deep secondary energy minimum; and (bottom) colloids separated from surface by more than ~ 100 nm due to large energy barrier. [Tong and Johnson, 2006]

Meiping Tong and husband

Dr. Meiping Tong and her husband.


Is it straining? Despite highly unfavorable attachment conditions, colloids attach to glass bead surfaces. Colloids (white dots) smaller than 4.5 micron attach predominantly to the open surface. Colloids larger than 4.5 micron attach predominantly in the grain to grain contacts. Arrows denote the main flow direction in each experiment. [Johnson et al., 2009]


Images showing attached colloids at different focal planes under unfavorable conditions. The images sweep through the surface of the collector (glass bead) from below (0.15 R and 0.3 R) to the center point of the collector (1.0 R). The images show that 0.21 micron colloids attach to the open surface of the beads (top panels), whereas the larger 9.0 micron colloids attach predominantly in the grain to grain contacts. [Johnson et al., 2009]


Development of new theory for colloid transport in porous media using Lagrangian force and torque balance [Johnson et al., 2007]



New collector for mechanistic prediction of colloid transport in porous media, includes physical grain to grain contact, which is demonstrated to be important for retention of larger colloids (~ > 2 micron) [Ma et al., 2009]


Dr. Huilian Ma

Prof. William Johnson | Frederick Albert Sutton Bldg | Rm 441 | 115 S. 1460 E. | Salt Lake City, UT | 84112
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